Ga2O3 Field-Effect-Transistor-Based Solar-Blind Photodetector With Fast Response and High Photo-to-Dark Current Ratio

A high-performancesolar-blind photodetector based on Cr-doped gallium oxide (Ga ₂ O ₃ ) has been fabricated. A 140-nm-thick Ga ₂ O ₃ layer was mechanically exfoliated from bulk crystal. The photodetector was based on a field-effect transistor structure, which showed a very high photo-to-dark current ratio larger than 106 and excellent current saturation. When the photodetector was tested with a 254-nm ultra-violet light, the ratio of drain current with and without the UV light reached nearly six orders of magnitude. The dark current was as low as 5 pA. Furthermore, the current rise time and decay time were both about 25 ms. High responsivity of 4.79 × 10 ⁵ A/W and external quantum efficiency of 2.34 × 10 ⁶ also have been achieved at the same time.